The purpose of this project is to describe and compare selected responses of preterm infants to breast and bottle feeding in order to expand the scientific base for nursing management of breast feeding. Currently, nursing interventions are based on the undocumented assumption that breast feeding is more stressful than bottle feeding for preterm infants. The question to be addressed in this project is "Is breast feeding an optimal method of feeding for preterm infants?". Phase I is a descriptive study in which the following measures will be made twice weekly for 40 clinically stable preterm infants from the time of initial oral feeding until hospital discharge: volume of intake during breast feeding, duration of the breast feeding session; infant weight, postconceptional age, and postnatal age at the time of breast feeding; and volume of intake during comparable bottle feedings. In Phase II the coordination of sucking, swallowing, and breathing will be compared for 40 clinically stable preterm infants during feeding: Group I infants will alternate bottle and breast feedings, serving as their own controls for the two feeding methods; Group II infants will bottle feed exclusively. This phase will test the hypotheses that: (a) bottle and breast feeding are associated with different patterns of coordinating sucking, swallowing, and breathing, with less interruption of breathing during breast feeding; and (b) these differences are most significant when infants are least mature. A pilot for Phase II will extend validity of instrumentation to measure sucking, swallowing, and breathing to preterm infants. In Phase III 20 clinically stable preterm infants will serve as their own controls for bottle and breast feeding to test the hypotheses that: (a) breast feeding is less stressful than bottle feeding, as measured by: coordination of sucking, swallowing, and breathing, transcutaneous oxygen pressure, transcutaneous carbon dioxide pressure, oxygen saturation, body temperature, heart rate, duration of the feeding session, and volume of intake; and (b) these differences are most significant when infants are least mature. Phase IV will describe the following parameters pre- and post- discharge for 25 clinically stable preterm infants who begin breast feeding at weights less than or equal to 1500 g, breast feed at least four times weekly until discharge, and transfer to complete breast feeding post-discharge: growth rates, frequency and duration of{breast feeding sessions; and maternal reactions to breast feeding preterm infants.